Detergent formulations employing alkali metal carbonates and/or alkali metal hydroxides are known to provide effective detergency, particularly when used with phosphorus-containing compounds. In particular, polyphosphates such as sodium tripolyphosphate and their salts are used in detergents because of their ability to prevent calcium carbonate precipitation and their ability to disperse and suspend soils. If calcium carbonate is allowed to precipitate, the crystals may attach to the surface being cleaned and cause undesirable effects. For example, calcium carbonate precipitation on the surface of ware can negatively impact the aesthetic appearance of the ware and give the ware an unclean look. In the laundering area, if calcium carbonate precipitates and attaches onto the surface of fabric, the crystals may leave the fabric feeling hard and rough to the touch. In addition to preventing the precipitation of calcium carbonate, the ability of sodium tripolyphosphate to disperse and suspend soils facilitates the detergency of the solution by preventing the soils from redepositing into the wash solution or wash water.
However, the use of phosphorous raw materials in detergents has become undesirable for a variety of reasons, including environmental reasons. This has resulted in heavy regulation of phosphorus emissions. Thus, industries are seeking alternative ways to control hard water scale formation associated with highly alkaline detergents. As noted above, many commercially-available detergent formulations have employed sodium tripolyphosphate as a cost effective warewashing detergent component for controlling hard water scale and similar benefits. However, as formulations are adapted to contain less than 0.5 wt-% phosphorus, there is a need for identifying replacement water conditioning and cleaning components. Many non-phosphate replacement formulations result in heavy soil accumulation on hard surfaces such as glass, plastic, rubber and/or metal surfaces, or less effective detergency.
Attempts have been made to provide the benefits of effective detergency, improved scale control, and improved soil dispersion without the use of phosphorus-containing compounds; however, these solutions have not been as effective as desired. For example, Savio et al., U.S. Pat. No. 5,152,910, Savio et al., U.S. Pat. No. 5,152,911, Savio et al., U.S. Pat. No. 5,279,756, and Savio et al., U.S. Pat. No. 5,281,352 used low-phosphate machine dishwashing compositions comprising acrylic polymer and maleic anhydride/olefin copolymer. Savio et al., U.S. Pat. No. 55,455,348 uses maleic acid homopolymer in a non-phosphate dishwashing detergent. Weber et al., U.S. Pat. No. 8,262,804 and Weber et al., E.P. No. 2,201,090 used phosphate-free dishwater detergent formulations containing a combination of hydrophobic modified polycarboxylates and hydrophilic modified polycarboxylates. Becker et al., U.S. Published Application No. 2008/0242577 employed hydrophobically modified polycarboxylates in rinsing agents. Van Boven et al., WO 2008/074402 uses polycarboxylic acid homopolymers and maleic acid or (meth)acrylic acid in soluble water softening compositions. Despite these efforts, effective warewash detergents having adequate scale control and soil dispersion with minimal or no phosphorus have not been developed.
Therefore, there is a need for detergent compositions, such as ware washing compositions, to provide adequate cleaning performance and preventing hard water scale accumulation while minimizing soil redeposition on a hard surfaces in contact with the detergent compositions. Similarly, there is a need for methods of reducing soil accumulation on a hard surface that avoids the use of phosphates.
Accordingly, it is an objective of the claimed invention to develop detergent compositions effective for reducing and/or substantially eliminating scale build up on hard surfaces while maintaining effective detergency.
A further object of the invention is to provide methods for employing alkaline detergents between pHs from about 9 to about 12.5 minimizing soil accumulation on hard surfaces.
A still further object of the invention is to employ alkaline detergents that are substantially free of phosphorus and exhibit improved control against hard water scale and prevent soil accumulation.
Other objects, advantages and features of the present invention will become apparent from the following specification taken in conjunction with the accompanying drawings.